How to Identify Sapient Species
I got into this discussion with a friend, and decided to post it here so more people can see it.
Most humans have an extremely limited perspective regarding sapience and its signs. Hell, they have a hard time recognizing a fishnet unless it's made of string. If it's made of rock, mud, or air, most of them won't recognize it. 0_o Me, I'm looking for things that catch fish.
I've permed a lot of the content from first contact training and planetary exploration in terms of how to identify near-sapient species that merit protection and sapient species with full personhood, so I will share that here.
Since nothing goes without saying given the execrable ethics of local-Earth, I will stipulate that in a responsible spacefaring civilization (which Earth is still trying to develop), common rules include:
* It is permissible to extract resources from any heavenly body in your territory which is devoid of detectable life.
* On bodies with low-level life (e.g. bacteria, algae, perhaps up through tiny crawling lifeforms such as worms or insects) there is a divergent trend:
-- In life-poor galaxies, any body with life typically gains some protections to avoid harm to that life.
-- In life-rich galaxies, there is often a minimum threshold of complexity before protections activate, because in those places almost every big enough body has something growing on it, the vast majority of which are simplistic. Because life is so ingenious, it is common for a galaxy to have lots of low-level life, but more complex life is often rarer due to its greater needs.
* Any biosphere of significant complexity, the definition of which varies somewhat by culture and context, gains substantial protections aimed at preserving it and also not accidentally transferring lifeforms elsewhere to cause trouble.
-- It is often permissible to harvest some things with little or no damage to the system integrity. People tend to argue over "how much" is permissible.
-- It is not permissible to cause extinctions or ravage ecosystems. Some people do it anyway, but in a responsible culture this is greatly scorned. (You will note that local-Earth does not qualify as civilized on a galactic scale, and would instead be classified with space pirates due to the level of environmental degradation.)
-- Don't forget to check for multiple ecosystems! Earth has at least two: the solar-powered one that humans live in, and the geothermal one around the black smokers. It is entirely possible, if less common, for a planet to have a hidden, more complex ecosystem while the surface is barren or simplistic.
-- Some cultures consider a biosphere itself to be a person, or close enough to a person to have some rights, by virtue of its complexity and responsiveness. Consider the Gaia Theory here on Earth, and living worlds or sapient planets in speculative fiction. The level of alertness and communication can vary greatly, but since sapience relies a lot on complexity, very large complex systems should definitely be considered. A problem here is communication across scope, as it is difficult to get the attention of something as big and (usually) slow as a planet. But if it seems to be responding in any mindful way to explorers, check immediately for other signs of sapience. Also stop bothering it before it decides to swat you like a fly.
* Any species that shows enough complexity to suggest intelligence and the potential for developing sapience is protected.
-- In galaxies that are life-rich but not also mind-rich, the protections are more vigorous. Sapience is viewed as a rare and precious resource to be defended whenever the potential is found. Galaxies that are life-poor are even more protective of it.
-- In galaxies that are both life-rich and mind-rich, the standards may be a little higher, but usually there is still at least some protection. A notable variation is that they may ban tampering with every proto-sapient species on a planet, but permit tampering with some of them so long as at least one remains. If you're used to having at least a handful underfoot most of the time, this makes more sense.
-- The rarest case is when sapience is so common that "weeding the garden" can actually benefit a biosphere by helping one or two more-fit proto-sapient species move forward without a dozen competitors dragging them down.
* Any species that demonstrates sapience is granted galactic personhood. Other sophonts may not intrude on their territory -- bothering someone else's homeworld is a great taboo -- and they have the right to expand into unclaimed space.
-- Distance of exclusive control from homeworld is often determined by level of technology, wherein species with far-traveling technology have a much larger sphere of influence than those with short-range technology. Compare with exclusive economic zones in Earth's oceans.
-- A common minimum is the home solar system. However, this may be reduced if more than one sapient species evolves in the same solar system, which tends to happen only in life-rich and relatively mind-rich galaxies. Note that the presence of Homo sapiens and multiple other species that are either proto-sapient or quite possibly sapient is a strong indication that this is a galaxy where life readily develops high complexity.
-- It is unethical to tamper with a sapient species or to steal their resources. This routinely starts arguments over whether a species is "really" sapient because it typically makes a planet hard-unavailable for colonization or other exploitation by outsiders (unless invited).
-- Ethical individuals and civilizations prefer to err on the side of caution when determining possible sapience. While they may miss out on some opportunities, they avoid a great many problems this way. Less-ethical, more-greedy ones tend to grab whatever they can, which routinely causes problems and sometimes wars. This is a common cause of galactic civilization collapse. Compare with causes of civilization collapse here.
-- Species with extremely different needs and tastes in galactic real estate sometimes manage to negotiate mutually beneficial arrangements whereby they share the divergent resources of the same territory. Common examples include aquatic/terrestrial, hot/cold, and any combination of different atmospheric requirements. Earth quite probably has cetacean sophonts holding almost 3/4 of the surface in the oceans, with Homo sapiens largely confined to the remaining 1/4 of solid land.
There are many signs of sapience, but there are few absolutes. The more signs a given species has, and the farther up the scale of probability those are, the more likely it is sapient. Just below that, a species may have one or a few signs; intelligent animals should be considered proto-sapient and not molested so that they can evolve however they will. Some sample clues of sapience include:
* Manipulatory appendages: A majority of sophonts have these. Some animals do, but it is much less common, and tends to appear in proto-sapients. This is because the development of manipulatory appendages for other purposes, such as food acquisition or climbing, provides a good foundation to become smarter. So they often appear before the intelligence ramps up. If you see something with hands, tentacles, or equivalent curiously manipulating its environment, you should leave it alone. This often appears as a requirement for sapience in systems of measurement, but remember that not all sophonts are obsessed with manipulating objects, and those who wish to alter their environment may use alternative methods (e.g. cetacean bubble technology is generated via their blowholes).
* Body size: Most sophonts are sort of medium-size, neither tiny nor giant. That doesn't mean ignore the other sizes, but if you are looking for sapient life, start in the middle.
-- Consider also the context, as some planets run to diminutive or enormous lifeforms due to local resources and conditions. A sapient species is most likely to emerge in the middle of its local size range, but the galactic average size range will be based on its laws of science, meaning that medium size is also a widespread possibility.
-- If you are able to check the evolutionary record, do so: a species may appear to be smaller or larger in current context, but drastic changes to the ecosystem have obscured its original position. Frex, humans appear larger in modern context with little megafauna left, but used to be much more firmly in the middle before most of the larger species died out.
* Brain size: The bigger the brain, and the larger in proportion to the rest of the body, the higher the chance of sapience. Thought processes require wetware to run on. Almost all sophonts have a large brain (or other neurological system) compared to body size.
-- Be aware that some smaller brains are more efficient or can connect in some way. Birds have more concise brains, allowing them to be smarter for their size compared to mammals. (Now remember that birds are dinosaurs, and consider whether the larger ones might have been even smarter.) Social insects have a sort of "hive mind" allowing them to function as a larger, more complex entity although the individual units tend to be pretty dumb. If anything seems to acting smarter than its size level would ordinarily suggest, suspect efficiency or communalism.
-- Some species have a "distributed" brain or set of brainlets, and more rarely the whole neural net has brain functions without a core mass of brain. If something acts relatively clever, but you cannot identify a brain, suspect that it is using a substitute and search for areas of activity within the body.
* Evolutionary level: Life is a syntropic process that strongly inclines toward greater complexity, thus sapience (an advanced feature) tends to appear more often later in the developmental timestream than earlier. So it's more likely in mammals than in fish, and so on.
-- However, age can play a role. A robust species or genus that has been around for ages has had time to experiment and find traits that are advantageous. Look at the hominid family tree for an example; it took a lot of fiddling to come up with Homo neanderthalensis and eventually Homo sapiens. Don't rule out an earlier form of life if it's showing signs of intelligence, especially if you have access to evolutionary records showing that it has advanced through multiple stages rather than just finding a decent form and sticking with that.
-- Be aware that species can move into and out of each other's sphere of reference. Highly-evolved and moderately-evolved sophonts may be using such different standards as to mistake each other for nonsapient animals. Frex, an advanced telepathic species may consider sapience based on quiet mental functions, while someone else at the level of speech and tool use is looking for audible language and physical artifacts. This can get very dangerous, so try to keep an open mind and remember that not all persons may resemble you.
* Group living: More sophonts live in groups than alone, as social interaction stimulates intelligence and permits cooperative activity. Don't rule out solitaries, but if you're seeking sophonts, start with cooperative groups.
-- Composite lifeforms, like jellyfish, are a bit of an oddity. Most planets decide that lifeforms will be either solitary or communal. The communal ones have an overwhelming advantage once they get a leg up, but it's harder for them to evolve fast enough to take over, because that level of cooperation is tricky to invent and maintain. Often you'll see just a few, like Earth's jellyfish; but if a cataclysm wipes out the singletons, the composites can make a break for the top with excellent odd of winning it. Like say, climate change. Trees can be surprisingly communal too.
-- Additionally, group-dwelling species have a great advantage in any mixed galactic civilization because their evolutionary path required the development of considerable social skills to maintain said group. They are thus better equipped to negotiate life in a mixed-species galaxy. Such civilizations are usually run by and for group-dwellers. Solitaries may be accommodated, or may (mutually or not) wind up keeping to themselves. Rarely, a species is solitary with regard to its conspecifics (due to territorial or other issues) but gets along just fine with others.
* Predator/prey dynamics: Sophonts are most often omnivores, sometimes carnivores, less often herbivores, and very rarely primary producers.
-- Omnivores have the great advantage of flexibility and the chance to gather many types of nutrients. However, they may evolve toward carnivory or herbivory if circumstances change over evolutionary timeframes.
-- Carnivores have the best access to meat, which is valuable in supporting biologically expensive brain tissue. Pack hunters are well equipped to develop sapience.
-- Herbivores are less prone to develop sapience, because their food doesn't run away. Sometimes they do so to defend against canny hunters. Also, they more often live in groups -- the largest animal groups are always herbivores or omnivores due to the energy pyramid -- and that goes well with sapience.
-- Primary producers are almost always plants or equivalent, with little incentive or opportunity for sentience. But it can happen. It is most prone to happen when the environment is so challenging that it demands dynamic response even from plants. In particular, keep an eye on carnivorous plants that can move quickly. This gives them a chance to evolve as did the amphibians crawling out of the sea to become air-breathers.
* Reproduction: Sophonts typically have a long childhood in which the parents care for their young. The smarter a creature, the more complex its culture, the longer it takes to learn everything it needs to know. Thus intelligent species tend to be more helpless at birth and stay with their parents a long time.
-- Altricial species are more likely to be sapient than precocial ones. Note that this matches the predator/prey dynamic above. Predatory or omnivorous species tend to be altricial, while herbivorous species tend to be precocial.
-- If you're looking for sophonts, start with the ones that have a lot of parent-child interaction. Don't rule out species with a short childhood or lack of parental care, as they may be using alternative means of development (e.g. telepathy, chemical transmission, metamorphosis, ancestral memories).
* Psychic abilities: This is a dead giveaway for sapience, except in places where it is ubiquitous. Usually a biosphere is strongly one way or the other, because this is such a massive advantage: nothing or almost nothing is psychic, or else everything or almost everything is. Unintelligent psychic organisms can exist, but are so vanishingly rare outside of psychic ecosystems that they should be treated as sapient.
* Ecosystem engineers: Dominant species have more opportunity to evolve intelligence, and sapient species are more prone to modify their environment for their own benefit. When examining a biosphere in search of sophonts, first aim to identify and study the keystone species. Using Earth as an example, and setting aside humans as obvious, both beavers and redwoods merit extra attention. More subtly still, so do wolves -- and they're strategizing pack hunters. Even more interesting, some wolves allied with another sapient species, humans, and became dogs -- perhaps tipping the dominance battle with another species, the Neanderthals.
* Abstraction: The ability to grasp that one thing can stand for another thing. This sets up for everything from maps to language and later writing, along with representational rather than abstract art. While not all sapient species use abstraction, most do, and it is almost never found below the near-sapient level of intelligent species that may later evolve sapience.
* Language: The more complex a creature's vocalizations, the more likely it is to be sapient. Language enables timebinding and greatly raises opportunities for social complexity.
-- Observed ability to transmit information is an extremely strong marker, though not quite a guarantee. However, the honeybee's ability to communicate complex information to coordinate foraging is a sign that this species could evolve sapience later.
-- Be aware that communication comes in extreme variety, and a species will use whatever is convenient. This can use sound, sight, smell, taste, touch, or other senses. It can happen in ranges not readily accessible to most humans or other exploratory species. Equip yourself with as much sensory equipment as possible and use it with an open mind. Communication may be at a faster or slower timeframe than the observer's too. Look for patterns atypical of natural ones, usually more complex and either highly variable or repeating a sequence. Look for patterns that respond to changes or events. Consider alien languages in speculative fiction and how we might identify something as language.
* Grief and mourning: Nonsapient animals rarely care about the dead, but most sophonts do, and a majority of cultures have rituals -- sometimes elaborate ones -- for the dead.
-- A few animals, such as great apes, elephants, and cetaceans have displayed some pretty dramatic signs of grief. If you shoot an alien critter and its herdmates flee, it may be an animal; if they gather around in conspicuous mourning, you probably just murdered someone.
-- Note that healthy galactic cultures tend to respect cultural differences, but a widespread taboo bans eating anything sapient, near-sapient, or possibly sapient as this constitutes a form of cannibalism.
* Tool use: Any manipulation of objects or processes in the environment to achieve goals is a strong sign of intelligence. This is uncommon but not unknown among nonsapient animals, but is much more likely the more advanced they get.
-- Making tools is a much stronger indicator. It's not a guarantee -- birds build nests, and most aren't sapient, but it does indicate that they're working with very efficient brains at their size. Compound tools constructed from several parts are also a big clue.
-- Cities are another really big clue. A few animals (ants, weaverbirds) build them, but it's rare, and those are species to watch in case they get smarter. Explore animal structures.
-- Control of chemical/physical processes (e.g. fire, ice, saponification, fermentation) is another very strong marker. Such use is rare in animals, but a few examples exist (like alligators building self-heating nests).
* Domestication: A species that in any way cultivates another species is more likely to be sentient. Sophonts frequently adopt plants, animals, or other lifeforms that are useful. These are protected from harm and selected for improved traits. It is rare but known for nonsapient animals to do this, as in fish or ants.
-- Because of this, the "domestication syndrome" is a vivid clue that a sapient species probably is (or at least was) nearby to cultivate that. While some features are particular to a given species or family, many are surprisingly widespread across animals or plants.
-- Be aware that not all types of agriculture look the same. A food forest, a plowed field, and a terraced rice paddy look nothing alike; an ant's aphid farm is different yet again. There are snow monkeys riding deer, and while it's rare for that to happen at such a low level, it can have very interesting results if it pans out.
* Behavioral clues: Many actions imply a mind. These tend to distinguish thoughtful from thoughtless lifeforms as observed in the wild.
-- Lying or other forms of deliberate deceit require: having a mind, realizing there are other minds, understanding what those minds think, predicting what they might do, and then acting to protect one's interests by misleading them. Animal deceit progresses through levels.
-- Strategy (as in hunting) and complex problem-solving (as in working a multi-stage puzzle box) require imagining a sequence of steps to obtain a goal. Most lifeforms cannot manage more than 1-2 steps, but intelligent ones can create much longer sequences.
-- Games and play are more sophisticated in sapient species. While many nonsapient animals play, especially while young, few of them use (let alone make) toys, and they don't use rules. Games with rules are strongly suggestive of sapience. Consider that while dogs will play with human-made toys and cats will bat at almost anything, dolphins make bubble-rings and play cooperatively (or perhaps competitively) with them.
-- Things an animal wouldn't do: sophonts have many reasons to do things, not all of those obvious. An animal might break into a camp searching for food, but is unlikely to try and figure out how a tool works.
-- Altruism: while known among animals, this is more common among sophonts, as it is a requirement of civilization.
-- Modesty and privacy: also required for civilization, although the amount varies. Animals very rarely cover themselves, but they do have a need for private space. This becomes more organized with intelligence. Some civilizations don't cover their bodies but instead use etiquette to manage how people interact.
-- Adornment: nonsapient animals rarely decorate themselves with objects or substances. Sapient species are much more prone to use clothes, jewelry, and other items for various purposes.
-- Cultural distinctions and cultural transmission of information. Most animals are guided by instinct and individual experience, with only modest educational efforts from parent to offspring. Near-sapient species, however, can learn by observation and may develop cultural differences across groups. Sapient species consistently develop culture, including many complex forms of cultural material, and diversity emerges when the population is large enough to split into subgroups.
Above all, remember: life finds a way, and the universe is stranger than most people can imagine. Observe. Think. Don't abuse other lifeforms. And don't act like an invasive species.
Most humans have an extremely limited perspective regarding sapience and its signs. Hell, they have a hard time recognizing a fishnet unless it's made of string. If it's made of rock, mud, or air, most of them won't recognize it. 0_o Me, I'm looking for things that catch fish.
I've permed a lot of the content from first contact training and planetary exploration in terms of how to identify near-sapient species that merit protection and sapient species with full personhood, so I will share that here.
Since nothing goes without saying given the execrable ethics of local-Earth, I will stipulate that in a responsible spacefaring civilization (which Earth is still trying to develop), common rules include:
* It is permissible to extract resources from any heavenly body in your territory which is devoid of detectable life.
* On bodies with low-level life (e.g. bacteria, algae, perhaps up through tiny crawling lifeforms such as worms or insects) there is a divergent trend:
-- In life-poor galaxies, any body with life typically gains some protections to avoid harm to that life.
-- In life-rich galaxies, there is often a minimum threshold of complexity before protections activate, because in those places almost every big enough body has something growing on it, the vast majority of which are simplistic. Because life is so ingenious, it is common for a galaxy to have lots of low-level life, but more complex life is often rarer due to its greater needs.
* Any biosphere of significant complexity, the definition of which varies somewhat by culture and context, gains substantial protections aimed at preserving it and also not accidentally transferring lifeforms elsewhere to cause trouble.
-- It is often permissible to harvest some things with little or no damage to the system integrity. People tend to argue over "how much" is permissible.
-- It is not permissible to cause extinctions or ravage ecosystems. Some people do it anyway, but in a responsible culture this is greatly scorned. (You will note that local-Earth does not qualify as civilized on a galactic scale, and would instead be classified with space pirates due to the level of environmental degradation.)
-- Don't forget to check for multiple ecosystems! Earth has at least two: the solar-powered one that humans live in, and the geothermal one around the black smokers. It is entirely possible, if less common, for a planet to have a hidden, more complex ecosystem while the surface is barren or simplistic.
-- Some cultures consider a biosphere itself to be a person, or close enough to a person to have some rights, by virtue of its complexity and responsiveness. Consider the Gaia Theory here on Earth, and living worlds or sapient planets in speculative fiction. The level of alertness and communication can vary greatly, but since sapience relies a lot on complexity, very large complex systems should definitely be considered. A problem here is communication across scope, as it is difficult to get the attention of something as big and (usually) slow as a planet. But if it seems to be responding in any mindful way to explorers, check immediately for other signs of sapience. Also stop bothering it before it decides to swat you like a fly.
* Any species that shows enough complexity to suggest intelligence and the potential for developing sapience is protected.
-- In galaxies that are life-rich but not also mind-rich, the protections are more vigorous. Sapience is viewed as a rare and precious resource to be defended whenever the potential is found. Galaxies that are life-poor are even more protective of it.
-- In galaxies that are both life-rich and mind-rich, the standards may be a little higher, but usually there is still at least some protection. A notable variation is that they may ban tampering with every proto-sapient species on a planet, but permit tampering with some of them so long as at least one remains. If you're used to having at least a handful underfoot most of the time, this makes more sense.
-- The rarest case is when sapience is so common that "weeding the garden" can actually benefit a biosphere by helping one or two more-fit proto-sapient species move forward without a dozen competitors dragging them down.
* Any species that demonstrates sapience is granted galactic personhood. Other sophonts may not intrude on their territory -- bothering someone else's homeworld is a great taboo -- and they have the right to expand into unclaimed space.
-- Distance of exclusive control from homeworld is often determined by level of technology, wherein species with far-traveling technology have a much larger sphere of influence than those with short-range technology. Compare with exclusive economic zones in Earth's oceans.
-- A common minimum is the home solar system. However, this may be reduced if more than one sapient species evolves in the same solar system, which tends to happen only in life-rich and relatively mind-rich galaxies. Note that the presence of Homo sapiens and multiple other species that are either proto-sapient or quite possibly sapient is a strong indication that this is a galaxy where life readily develops high complexity.
-- It is unethical to tamper with a sapient species or to steal their resources. This routinely starts arguments over whether a species is "really" sapient because it typically makes a planet hard-unavailable for colonization or other exploitation by outsiders (unless invited).
-- Ethical individuals and civilizations prefer to err on the side of caution when determining possible sapience. While they may miss out on some opportunities, they avoid a great many problems this way. Less-ethical, more-greedy ones tend to grab whatever they can, which routinely causes problems and sometimes wars. This is a common cause of galactic civilization collapse. Compare with causes of civilization collapse here.
-- Species with extremely different needs and tastes in galactic real estate sometimes manage to negotiate mutually beneficial arrangements whereby they share the divergent resources of the same territory. Common examples include aquatic/terrestrial, hot/cold, and any combination of different atmospheric requirements. Earth quite probably has cetacean sophonts holding almost 3/4 of the surface in the oceans, with Homo sapiens largely confined to the remaining 1/4 of solid land.
There are many signs of sapience, but there are few absolutes. The more signs a given species has, and the farther up the scale of probability those are, the more likely it is sapient. Just below that, a species may have one or a few signs; intelligent animals should be considered proto-sapient and not molested so that they can evolve however they will. Some sample clues of sapience include:
* Manipulatory appendages: A majority of sophonts have these. Some animals do, but it is much less common, and tends to appear in proto-sapients. This is because the development of manipulatory appendages for other purposes, such as food acquisition or climbing, provides a good foundation to become smarter. So they often appear before the intelligence ramps up. If you see something with hands, tentacles, or equivalent curiously manipulating its environment, you should leave it alone. This often appears as a requirement for sapience in systems of measurement, but remember that not all sophonts are obsessed with manipulating objects, and those who wish to alter their environment may use alternative methods (e.g. cetacean bubble technology is generated via their blowholes).
* Body size: Most sophonts are sort of medium-size, neither tiny nor giant. That doesn't mean ignore the other sizes, but if you are looking for sapient life, start in the middle.
-- Consider also the context, as some planets run to diminutive or enormous lifeforms due to local resources and conditions. A sapient species is most likely to emerge in the middle of its local size range, but the galactic average size range will be based on its laws of science, meaning that medium size is also a widespread possibility.
-- If you are able to check the evolutionary record, do so: a species may appear to be smaller or larger in current context, but drastic changes to the ecosystem have obscured its original position. Frex, humans appear larger in modern context with little megafauna left, but used to be much more firmly in the middle before most of the larger species died out.
* Brain size: The bigger the brain, and the larger in proportion to the rest of the body, the higher the chance of sapience. Thought processes require wetware to run on. Almost all sophonts have a large brain (or other neurological system) compared to body size.
-- Be aware that some smaller brains are more efficient or can connect in some way. Birds have more concise brains, allowing them to be smarter for their size compared to mammals. (Now remember that birds are dinosaurs, and consider whether the larger ones might have been even smarter.) Social insects have a sort of "hive mind" allowing them to function as a larger, more complex entity although the individual units tend to be pretty dumb. If anything seems to acting smarter than its size level would ordinarily suggest, suspect efficiency or communalism.
-- Some species have a "distributed" brain or set of brainlets, and more rarely the whole neural net has brain functions without a core mass of brain. If something acts relatively clever, but you cannot identify a brain, suspect that it is using a substitute and search for areas of activity within the body.
* Evolutionary level: Life is a syntropic process that strongly inclines toward greater complexity, thus sapience (an advanced feature) tends to appear more often later in the developmental timestream than earlier. So it's more likely in mammals than in fish, and so on.
-- However, age can play a role. A robust species or genus that has been around for ages has had time to experiment and find traits that are advantageous. Look at the hominid family tree for an example; it took a lot of fiddling to come up with Homo neanderthalensis and eventually Homo sapiens. Don't rule out an earlier form of life if it's showing signs of intelligence, especially if you have access to evolutionary records showing that it has advanced through multiple stages rather than just finding a decent form and sticking with that.
-- Be aware that species can move into and out of each other's sphere of reference. Highly-evolved and moderately-evolved sophonts may be using such different standards as to mistake each other for nonsapient animals. Frex, an advanced telepathic species may consider sapience based on quiet mental functions, while someone else at the level of speech and tool use is looking for audible language and physical artifacts. This can get very dangerous, so try to keep an open mind and remember that not all persons may resemble you.
* Group living: More sophonts live in groups than alone, as social interaction stimulates intelligence and permits cooperative activity. Don't rule out solitaries, but if you're seeking sophonts, start with cooperative groups.
-- Composite lifeforms, like jellyfish, are a bit of an oddity. Most planets decide that lifeforms will be either solitary or communal. The communal ones have an overwhelming advantage once they get a leg up, but it's harder for them to evolve fast enough to take over, because that level of cooperation is tricky to invent and maintain. Often you'll see just a few, like Earth's jellyfish; but if a cataclysm wipes out the singletons, the composites can make a break for the top with excellent odd of winning it. Like say, climate change. Trees can be surprisingly communal too.
-- Additionally, group-dwelling species have a great advantage in any mixed galactic civilization because their evolutionary path required the development of considerable social skills to maintain said group. They are thus better equipped to negotiate life in a mixed-species galaxy. Such civilizations are usually run by and for group-dwellers. Solitaries may be accommodated, or may (mutually or not) wind up keeping to themselves. Rarely, a species is solitary with regard to its conspecifics (due to territorial or other issues) but gets along just fine with others.
* Predator/prey dynamics: Sophonts are most often omnivores, sometimes carnivores, less often herbivores, and very rarely primary producers.
-- Omnivores have the great advantage of flexibility and the chance to gather many types of nutrients. However, they may evolve toward carnivory or herbivory if circumstances change over evolutionary timeframes.
-- Carnivores have the best access to meat, which is valuable in supporting biologically expensive brain tissue. Pack hunters are well equipped to develop sapience.
-- Herbivores are less prone to develop sapience, because their food doesn't run away. Sometimes they do so to defend against canny hunters. Also, they more often live in groups -- the largest animal groups are always herbivores or omnivores due to the energy pyramid -- and that goes well with sapience.
-- Primary producers are almost always plants or equivalent, with little incentive or opportunity for sentience. But it can happen. It is most prone to happen when the environment is so challenging that it demands dynamic response even from plants. In particular, keep an eye on carnivorous plants that can move quickly. This gives them a chance to evolve as did the amphibians crawling out of the sea to become air-breathers.
* Reproduction: Sophonts typically have a long childhood in which the parents care for their young. The smarter a creature, the more complex its culture, the longer it takes to learn everything it needs to know. Thus intelligent species tend to be more helpless at birth and stay with their parents a long time.
-- Altricial species are more likely to be sapient than precocial ones. Note that this matches the predator/prey dynamic above. Predatory or omnivorous species tend to be altricial, while herbivorous species tend to be precocial.
-- If you're looking for sophonts, start with the ones that have a lot of parent-child interaction. Don't rule out species with a short childhood or lack of parental care, as they may be using alternative means of development (e.g. telepathy, chemical transmission, metamorphosis, ancestral memories).
* Psychic abilities: This is a dead giveaway for sapience, except in places where it is ubiquitous. Usually a biosphere is strongly one way or the other, because this is such a massive advantage: nothing or almost nothing is psychic, or else everything or almost everything is. Unintelligent psychic organisms can exist, but are so vanishingly rare outside of psychic ecosystems that they should be treated as sapient.
* Ecosystem engineers: Dominant species have more opportunity to evolve intelligence, and sapient species are more prone to modify their environment for their own benefit. When examining a biosphere in search of sophonts, first aim to identify and study the keystone species. Using Earth as an example, and setting aside humans as obvious, both beavers and redwoods merit extra attention. More subtly still, so do wolves -- and they're strategizing pack hunters. Even more interesting, some wolves allied with another sapient species, humans, and became dogs -- perhaps tipping the dominance battle with another species, the Neanderthals.
* Abstraction: The ability to grasp that one thing can stand for another thing. This sets up for everything from maps to language and later writing, along with representational rather than abstract art. While not all sapient species use abstraction, most do, and it is almost never found below the near-sapient level of intelligent species that may later evolve sapience.
* Language: The more complex a creature's vocalizations, the more likely it is to be sapient. Language enables timebinding and greatly raises opportunities for social complexity.
-- Observed ability to transmit information is an extremely strong marker, though not quite a guarantee. However, the honeybee's ability to communicate complex information to coordinate foraging is a sign that this species could evolve sapience later.
-- Be aware that communication comes in extreme variety, and a species will use whatever is convenient. This can use sound, sight, smell, taste, touch, or other senses. It can happen in ranges not readily accessible to most humans or other exploratory species. Equip yourself with as much sensory equipment as possible and use it with an open mind. Communication may be at a faster or slower timeframe than the observer's too. Look for patterns atypical of natural ones, usually more complex and either highly variable or repeating a sequence. Look for patterns that respond to changes or events. Consider alien languages in speculative fiction and how we might identify something as language.
* Grief and mourning: Nonsapient animals rarely care about the dead, but most sophonts do, and a majority of cultures have rituals -- sometimes elaborate ones -- for the dead.
-- A few animals, such as great apes, elephants, and cetaceans have displayed some pretty dramatic signs of grief. If you shoot an alien critter and its herdmates flee, it may be an animal; if they gather around in conspicuous mourning, you probably just murdered someone.
-- Note that healthy galactic cultures tend to respect cultural differences, but a widespread taboo bans eating anything sapient, near-sapient, or possibly sapient as this constitutes a form of cannibalism.
* Tool use: Any manipulation of objects or processes in the environment to achieve goals is a strong sign of intelligence. This is uncommon but not unknown among nonsapient animals, but is much more likely the more advanced they get.
-- Making tools is a much stronger indicator. It's not a guarantee -- birds build nests, and most aren't sapient, but it does indicate that they're working with very efficient brains at their size. Compound tools constructed from several parts are also a big clue.
-- Cities are another really big clue. A few animals (ants, weaverbirds) build them, but it's rare, and those are species to watch in case they get smarter. Explore animal structures.
-- Control of chemical/physical processes (e.g. fire, ice, saponification, fermentation) is another very strong marker. Such use is rare in animals, but a few examples exist (like alligators building self-heating nests).
* Domestication: A species that in any way cultivates another species is more likely to be sentient. Sophonts frequently adopt plants, animals, or other lifeforms that are useful. These are protected from harm and selected for improved traits. It is rare but known for nonsapient animals to do this, as in fish or ants.
-- Because of this, the "domestication syndrome" is a vivid clue that a sapient species probably is (or at least was) nearby to cultivate that. While some features are particular to a given species or family, many are surprisingly widespread across animals or plants.
-- Be aware that not all types of agriculture look the same. A food forest, a plowed field, and a terraced rice paddy look nothing alike; an ant's aphid farm is different yet again. There are snow monkeys riding deer, and while it's rare for that to happen at such a low level, it can have very interesting results if it pans out.
* Behavioral clues: Many actions imply a mind. These tend to distinguish thoughtful from thoughtless lifeforms as observed in the wild.
-- Lying or other forms of deliberate deceit require: having a mind, realizing there are other minds, understanding what those minds think, predicting what they might do, and then acting to protect one's interests by misleading them. Animal deceit progresses through levels.
-- Strategy (as in hunting) and complex problem-solving (as in working a multi-stage puzzle box) require imagining a sequence of steps to obtain a goal. Most lifeforms cannot manage more than 1-2 steps, but intelligent ones can create much longer sequences.
-- Games and play are more sophisticated in sapient species. While many nonsapient animals play, especially while young, few of them use (let alone make) toys, and they don't use rules. Games with rules are strongly suggestive of sapience. Consider that while dogs will play with human-made toys and cats will bat at almost anything, dolphins make bubble-rings and play cooperatively (or perhaps competitively) with them.
-- Things an animal wouldn't do: sophonts have many reasons to do things, not all of those obvious. An animal might break into a camp searching for food, but is unlikely to try and figure out how a tool works.
-- Altruism: while known among animals, this is more common among sophonts, as it is a requirement of civilization.
-- Modesty and privacy: also required for civilization, although the amount varies. Animals very rarely cover themselves, but they do have a need for private space. This becomes more organized with intelligence. Some civilizations don't cover their bodies but instead use etiquette to manage how people interact.
-- Adornment: nonsapient animals rarely decorate themselves with objects or substances. Sapient species are much more prone to use clothes, jewelry, and other items for various purposes.
-- Cultural distinctions and cultural transmission of information. Most animals are guided by instinct and individual experience, with only modest educational efforts from parent to offspring. Near-sapient species, however, can learn by observation and may develop cultural differences across groups. Sapient species consistently develop culture, including many complex forms of cultural material, and diversity emerges when the population is large enough to split into subgroups.
Above all, remember: life finds a way, and the universe is stranger than most people can imagine. Observe. Think. Don't abuse other lifeforms. And don't act like an invasive species.